Electric motor and working machine

Abstract

To provide an electric motor and a working machine capable of improving cooling performance.SOLUTION: An electric motor includes a housing that accommodates a rotor and a stator, and a heat exchange portion that is integrated into the housing and cools a cooling fluid. The heat exchange portion includes a heat exchange passage formed on a side surface of the housing. The heat exchange passage satisfies A1>A2, when a flow path cross-sectional area at a first position in the fluid flow direction is defined as a first area A1 and a flow path cross-sectional area at a second position downstream of the first position in the fluid flow direction is defined as a second area A2.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present disclosure relates to electric motors and work machines. [Background technology]

[0002] Conventionally, an electric rotating shovel equipped with an electric motor for rotating an upper rotating body has been known as a construction machine. The electric motor is equipped with a cooling circuit for cooling a rotor, a stator, etc. provided therein with cooling oil. The cooling oil flowing out from a cooling oil outlet port of the cooling circuit is sent to a cooling fluid pump and circulates through the cooling circuit again to cool the electric motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-005289 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, there is a risk that the electric motor may not be sufficiently cooled with the configuration of Patent Document 1. If the electric motor is not sufficiently cooled, loss may increase and the performance of the electric motor may deteriorate.

[0005] An object of an aspect of the present disclosure is to provide an electric motor and a work machine that can improve cooling performance. [Means for solving the problem]

[0006] An electric motor according to one embodiment of the present disclosure comprises a housing that accommodates a rotor and a stator, and a heat exchange unit that is integrated into the housing and cools a cooling fluid, the heat exchange unit including a heat exchange passage formed on a side surface of the housing, and when a flow path cross-sectional area at a first position in the fluid flow direction is defined as a first area A1 and a flow path cross-sectional area at a second position downstream of the first position in the fluid flow direction is defined as a second area A2, A1>A2 is satisfied. Effect of the Invention

[0007] According to the aspects of the present disclosure, it is possible to provide an electric motor and a work machine that can improve cooling performance. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing a work machine according to an embodiment. [Diagram 2] 1 is a diagram showing a drive system of a work machine according to an embodiment. [Diagram 3] 1 is a perspective view of an electric motor according to an embodiment; [Figure 4] 1 is a cross-sectional view of an electric motor according to an embodiment. [Diagram 5] FIG. 4 is an explanatory diagram of flows of cooling oil and cooling water according to the embodiment. [Figure 6] FIG. 4 is an explanatory diagram of an arrangement of a heat exchanger with respect to a first cooling circuit according to the embodiment. [Figure 7] FIG. 4 is an explanatory diagram of a flow path cross-sectional area of ​​a heat exchange passage according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In this embodiment, an electric motor is mounted on an electric slewing shovel (an example of a work machine) and is configured as a swing motor for swinging an upper swing body of the electric slewing shovel.

[0010] In the following description, expressions indicating relative or absolute arrangements, such as "parallel," "orthogonal," "center," and "coaxial," do not only mean such arrangements or states strictly, but also include arrangements or states in which there is a relative displacement with an angle or distance to the extent that the same function can be obtained with a tolerance. In the drawings used in the following description, the scale of each component may be appropriately changed to show each component with a recognizable size.

[0011] <Work machinery> Fig. 1 is a schematic diagram showing a work machine according to an embodiment. The work machine 100 according to this embodiment is an electric hydraulic excavator. The work machine 100 may be a manned vehicle that is operated by a driver, or an unmanned vehicle that is operated without a driver.

[0012] The work machine 100 includes a running body 120 , an upper rotating body 140 , and a work implement 160 .

[0013] The running body 120 supports the work machine 100 so that it can run. The running body 120 is equipped with a running device 121. The running device 121 is, for example, a pair of left and right caterpillar tracks. The running device 121 is driven by a traveling motor 122. The upper rotating body 140 is supported on the running body 120 so as to be rotatable about a rotation axis. The upper rotating body 140 performs a rotating operation relative to the running body 120 by the rotation motor 114. The upper rotating body 140 has a compartment 141 that houses a drive system.

[0014] The working machine 160 is supported movably on the upper rotating body 140. The working machine 160 is hydraulically driven. The working machine 160 includes a boom 161, an arm 162, and an attachment 163. The attachment 163 is an example of a working tool. In the example shown in FIG. 1, the attachment 163 is a bucket. In the example shown in FIG. 1, the side of the upper rotating body 140 on which the working machine 160 is supported is the front, and the opposite side with respect to the front is the rear. In this embodiment, the left-right direction refers to the left and right with respect to the front, and the up-down direction refers to the direction in which the rotation axis of the upper rotating body 140 extends.

[0015] <Work machine drive system> 2 is a diagram showing a drive system of a work machine according to an embodiment. The work machine 100 is equipped with a plurality of actuators for driving the work machine 100. The work machine 100 is equipped with an electricity storage device 111, a power supply device 112, a prime mover 113, a swing motor 114, a hydraulic pump 115, a control valve 116, a boom cylinder 117, an arm cylinder 118, an attachment cylinder 119, and a pair of travel motors 122. The electricity storage device 111, the power supply device 112, the prime mover 113, the swing motor 114, the hydraulic pump 115, and the control valve 116 are housed in a compartment 141.

[0016] The power storage device 111 supplies electric power, which is a power source for driving the work machine 100. The power storage device 111 is, for example, a battery or a capacitor. The power storage device 111 supplies electric power to the prime mover 113 and the swing motor 114 via a power supply device 112. The power supply device 112 controls the supplied electric power in accordance with the load. The power supply device 112 is, for example, an inverter device.

[0017] The prime mover 113 is an electric motor that is driven by electric power supplied from the power storage device 111. The prime mover 113 drives a hydraulic pump 115. Note that the prime mover 113 may be, for example, an internal combustion engine.

[0018] The swing motor 114 is an electric motor that is driven by power supplied from the power storage device 111. The swing motor 114 swings the upper swing body 140 relative to the traveling body 120.

[0019] The hydraulic pump 115 is driven by the prime mover 113, and supplies hydraulic oil to the boom cylinder 117, the arm cylinder 118, the attachment cylinder 119, and the traveling motor 122 via a control valve 116. The control valve 116 controls the flow rate of hydraulic oil supplied from the hydraulic pump 115 to the traveling motor 122, the boom cylinder 117, the arm cylinder 118, and the attachment cylinder 119. The traveling motor 122 is driven by the hydraulic oil supplied from the hydraulic pump 115, and operates the traveling device 121.

[0020] The boom cylinder 117 is a hydraulic cylinder for operating the boom 161 relative to the upper rotating body 140. The arm cylinder 118 is a hydraulic cylinder for operating the arm 162 relative to the boom 161. The attachment cylinder 119 is a hydraulic cylinder for operating the attachment 163 relative to the arm 162.

[0021] <Electric motor> Fig. 3 is a perspective view of the electric motor 1 according to the embodiment. Fig. 4 is a cross-sectional view of the electric motor 1 according to the embodiment. Fig. 5 is an explanatory diagram of the flows of cooling oil and cooling water according to the embodiment. Hereinafter, the cooling oil may be simply referred to as "oil" and the cooling water may be simply referred to as "water".

[0022] In this embodiment, the electric motor 1 is a swivel motor 114. The electric motor 1 includes a rotor 2, a stator 3, and a housing 4 that accommodates the rotor 2 and the stator 3. The electric motor 1 is an inner rotor type motor in which the stator 3 is disposed outside the cylindrical rotor 2. The electric motor 1 is placed vertically so that the rotor shaft 20 of the rotor 2 is parallel to the swivel axis.

[0023] In this embodiment, the upper side corresponds to one side parallel to the central axis CL of the rotor shaft 20, and the lower side corresponds to the other side parallel to the central axis CL of the rotor shaft 20. Hereinafter, the direction along the central axis CL of the rotor shaft 20 is referred to as the "axial direction", the direction perpendicular to the axial direction is referred to as the "radial direction", and the direction going around the central axis CL of the rotor shaft 20 is referred to as the "circumferential direction".

[0024] The rotor 2 includes a rotor shaft 20, a rotor core 21, an upper plate 22, and a lower plate 23. The rotor shaft 20 is rotatably supported relative to the housing 4 by bearings 21A and 21B.

[0025] The rotor core 21 is formed, for example, by laminating electromagnetic steel sheets in the axial direction. The rotor core 21 is fitted onto the rotor shaft 20. The rotor core 21 rotates integrally with the rotor shaft 20. A plurality of permanent magnets (not shown) are embedded in the rotor core 21.

[0026] Each of the upper plate 22 and the lower plate 23 is annular plate members arranged coaxially with the rotor shaft 20. The upper plate 22 and the lower plate 23 are fitted to the rotor shaft 20. The upper plate 22 and the lower plate 23 hold the rotor core 21 from the outside in the axial direction. The upper plate 22 and the lower plate 23 rotate integrally with the rotor shaft 20 and the rotor core 21.

[0027] The stator 3 is fixed to the inner surface of the housing 4 so as to cover the outer periphery of the rotor 2. The stator 3 includes a cylindrical stator core 30 and a stator coil 31. Like the rotor core 21, the stator core 30 is formed by laminating electromagnetic steel sheets in the axial direction. A plurality of teeth (not shown) are provided circumferentially on the inner periphery of the stator core 30. The stator coil 31 is wound around the teeth.

[0028] The housing 4 accommodates the rotor 2 and the stator 3. The housing 4 includes a cylindrical body 10, a ceiling portion 11 that closes an upper opening of the cylinder 10, and a bottom portion 13 that closes a lower opening of the cylinder 10. A space 40 for accommodating the rotor 2 and the stator 3 is formed inside the housing 4 by the cylinder 10, the ceiling portion 11, and the bottom portion 13.

[0029] The heat exchange section 7 is integrally formed with the cylinder 10. The ceiling section 11 is provided with a second fluid supply passage 12 for introducing cooling fluid into the space 40. The bottom section 13 is provided with a fluid reservoir 15 for temporarily storing the cooling fluid flowing through the space 40 via the second cooling fluid supply passage 12. The bottom section 13 is provided with a second fluid discharge passage 16 that communicates with the fluid reservoir 15 and discharges the cooling fluid from the space 40.

[0030] The electric motor 1 includes a first cooling circuit 6 through which a first fluid flows, and a second cooling circuit 5 through which a second fluid different from the first fluid flows. The first cooling circuit 6 is formed integrally with a cylindrical body 10 of the housing 4. The second cooling circuit 5 is composed of a second fluid supply passage 12, a fluid reservoir 15, and a second fluid discharge passage 16.

[0031] In this embodiment, cooling water flows as a first fluid in the first cooling circuit 6. The first cooling circuit 6 is a circuit (hereinafter also referred to as a "cooling water circuit") that uses cooling water to cool the electric motor 1 from the outer periphery of the stator 3. On the other hand, cooling oil flows as a second fluid in the second cooling circuit 5. The second cooling circuit 5 is a circuit (hereinafter also referred to as a "cooling oil circuit") for directly cooling members such as the rotor 2 housed in the space 40 with cooling oil. The heat exchanger 7 is an oil cooler for cooling the cooling oil. The heat exchanger 7 may be a radiator that cools the cooling water. The heat exchanger 7 cools at least one of the first fluid and the second fluid.

[0032] 3 and 4, the electric motor 1 is configured so that the cooling oil discharged from the cooling fluid pump 8 flows from the second fluid supply passage 12 into the space 40 via the heat exchanger 7. The electric motor 1 is configured so that the cooling oil that has passed through the heat exchanger 7 flows into the fluid reservoir 15 via a passage 53 formed in the rotor shaft 20, a groove 54 formed in the lower plate 23, a through passage 55 formed in the rotor core 21, and a cooling oil ejection hole 56 formed in the upper plate 22.

[0033] The first cooling circuit 6 is composed of a first fluid supply port 60 and a first fluid discharge port 61 formed in the cylindrical body 10 of the housing 4, and a water jacket 62 formed inside the cylindrical body 10. The water jacket 62 communicates with the first fluid supply port 60 and the first fluid discharge port 61 on the upper side of the cylindrical body 10.

[0034] 6 is an explanatory diagram of the arrangement of the heat exchange section 7 with respect to the first cooling circuit 6 according to the embodiment. 5 and 6, the first cooling circuit 6 has a water jacket 62 (an example of a first fluid passage) that is continuous in the circumferential direction of the cylinder 10 while passing through the inside of the cylinder 10 and meandering in one direction and the other direction parallel to the central axis CL of the rotor shaft 20. The water jacket 62 is composed of a plurality of straight passages 62A formed in a straight line parallel to the central axis CL and arranged at intervals in the circumferential direction, a one-end side passage 62B formed to connect two one-end sides of the plurality of straight passages 62A that are adjacent to each other in the circumferential direction, and an other-end side passage 62C formed to connect two other-end sides of the plurality of straight passages 62A that are adjacent to each other in the circumferential direction and arranged alternately with the one-end side passage 62B in the circumferential direction.

[0035] In this embodiment, the straight passage 62A is a passage formed in a straight line along the vertical direction (hereinafter also referred to as a "vertical straight passage"). The one end side passage 62B is a passage formed along the horizontal direction (specifically, the circumferential direction of the cylindrical body 10) so as to connect the upper end sides of the two vertical straight passages 62A adjacent to each other in the circumferential direction (hereinafter also referred to as an "upper horizontal passage"). The other end side passage 62C is a passage formed along the horizontal direction (specifically, the circumferential direction of the cylindrical body 10) so as to connect the lower end sides of the two vertical straight passages 62A adjacent to each other in the circumferential direction (hereinafter also referred to as a "lower horizontal passage"). In this embodiment, the multiple vertical straight passages 62A include a first straight passage 62A1, a second straight passage 62A2, and a third straight passage 62A3 that are arranged in sequence at intervals in the circumferential direction.

[0036] 6, the vertical straight passage 62A, the upper horizontal passage 62B, and the lower horizontal passage 62C are shown to have substantially the same flow passage cross-sectional area and a straight flow passage shape, but are not limited to the above. For example, if there is a part in the cylindrical body 10 that is to be actively cooled, the size of the flow passage cross-sectional area and the flow passage shape may be any mode that takes into account the position of such a part. The modes of the vertical straight passage 62A, the upper horizontal passage 62B, and the lower horizontal passage 62C can be changed according to design specifications.

[0037] <Heat exchange section> 3 to 6, the heat exchange portion 7 is integrally formed with a part of the outer periphery of the cylindrical body 10. As shown in FIG.

[0038] When viewed from one side of the cylinder 10, the heat exchange unit 7 overlaps with a part of the water jacket 62. When viewed from one side of the cylinder 10, the heat exchange unit 7 overlaps with one of the multiple straight passages 62A. When viewed from one side of the cylinder 10, the heat exchange unit 7 is disposed between the upper horizontal passage 62B and the lower horizontal passage 62C. When viewed from one side of the cylinder 10, the heat exchange unit 7 is disposed between the first straight passage 62A1 and the third straight passage 62A3, and overlaps with the second straight passage 62A2.

[0039] In this embodiment, as shown in FIG. 5, when viewed from one side of the cylinder 10, the heat exchange section 7 has a heat exchange passage 70 that intersects with one of the multiple straight passages 62A and continues in a direction parallel to the central axis CL while meandering in one direction and the other.

[0040] When viewed from one side of the cylinder 10, the heat exchange passage 70 is composed of a passage 70A (hereinafter also referred to as the "heat exchange horizontal passage 70A") formed along a horizontal direction (specifically, the circumferential direction of the cylinder 10) intersecting with the second straight passage 62A2, a one-end side passage 70B (hereinafter also referred to as the "first end side communication passage 70B") formed along the vertical direction so as to connect the horizontal one-end sides of two heat exchange horizontal passages 70A adjacent to each other in the vertical direction, and an other-end side passage 70C (hereinafter also referred to as the "second end side communication passage 70C") formed along the vertical direction so as to connect the horizontal other-end sides of two heat exchange horizontal passages 70A adjacent to each other in the vertical direction. The first end side communication passage 70B and the second end side communication passage 70C are arranged alternately in the vertical direction.

[0041] 5, the heat exchange horizontal passage 70A, the first end side communicating passage 70B, and the second end side communicating passage 70C are shown in part as having substantially equal flow passage cross-sectional areas and linear flow passage shapes, but are not limited thereto. For example, in the case where there is a portion in the heat exchange section 7 that is to be actively cooled, the flow passage cross-sectional area and flow passage shape may be any shape that takes into account the position of such a portion. The shapes of the heat exchange horizontal passage 70A, the first end side communicating passage 70B, and the second end side communicating passage 70C can be changed according to design specifications.

[0042] The heat exchange section 7 includes a wall section 71 that opens the heat exchange passage 70 to one side of the cylindrical body 10, and a lid section 72 that is connected to the wall section 71 and closes the heat exchange passage 70 from one side of the cylindrical body 10. Although not shown, a seal member may be provided between the wall section 71 and the lid section 72.

[0043] The lid portion 72 is fixed to the wall portion 71 by a fastening member such as a bolt 73. An internal thread 74 into which the external thread of the bolt 73 screws is formed on the outer edge of the wall portion 71. An insertion hole (not shown) through which the bolt 73 is inserted is formed in the lid portion 72. For example, with the heat exchange passage 70 of the wall portion 71 blocked from one side of the cylindrical body 10 by the lid portion 72, the bolt 73 is inserted into the insertion hole of the lid portion 72 and screwed into the internal thread 74. This allows the lid portion 72 to be fixed to the wall portion 71.

[0044] In the illustrated example, the cover portion 72 is fixed to the wall portion 71 by a bolt 73. In the illustrated example, a female thread 74 is formed in the wall portion 71. Note that the number of bolts 73 and the number and location of the female threads 74 are not limited to the above and can be changed according to the design specifications.

[0045] An inlet 75 for introducing cooling oil into the heat exchange passage 70 is formed at one end of the wall portion 71 in a direction parallel to the central axis CL. Further, an outlet 76 for discharging cooling oil from the heat exchange passage 70 is formed at the other end of the wall portion 71 in a direction parallel to the central axis CL. In this embodiment, the inlet 75 is formed in a portion on the lower end side of the wall portion 71, and the outlet 76 is formed in a portion on the upper end side of the wall portion 71. The inlet 75 and the outlet 76 are disposed on the same side of the wall portion 71 in the horizontal direction.

[0046] For example, the exhaust outlet 76 may be disposed on the side opposite to the side where the inlet 75 is disposed, or the inlet 75 and the exhaust outlet 76 may be disposed on different sides. Note that the arrangement of the inlet 75 and the exhaust outlet 76 is not limited to the above and can be changed according to the design specifications.

[0047] <Cooling oil flow> 3 and 5, for example, cooling oil supplied from a cooling fluid pump flows into the inlet 75 of the heat exchanger 7. The cooling oil that flows into the inlet 75 of the heat exchanger 7 passes through the heat exchange passage 70 of the heat exchanger 7 and flows out from the outlet 76. The cooling oil that flows out from the outlet 76 of the heat exchanger 7 is sent to the inside of the electric motor 1.

[0048] 4, specifically, the cooling oil discharged from the outlet 76 of the heat exchange unit 7 flows into the second fluid supply passage 12 from the cooling oil inlet 50. The cooling oil that flows into the second fluid supply passage 12 is divided into the passage 53 of the rotor shaft 20 and a bearing cooling passage (not shown). The cooling oil that flows into the bearing cooling passage flows out into the outer ring portion of the upper bearing 21A to lubricate and cool the bearing 21A.

[0049] Meanwhile, when the cooling oil that has flowed into the passages 53 of the rotor shaft 20 flows to the lower end of the passages 53, it passes through the grooves 54 of the lower plate 23 and the through passages 55 of the rotor core 21 to cool the rotor 2. The cooling oil that has passed through the through passages 55 is ejected from the cooling oil ejection holes 56 of the upper plate 22 into the cylinder 10. The cooling oil ejected into the cylinder 10 falls while cooling the stator coil 31, and lubricates and cools the lower bearing 21B.

[0050] The cooling oil that has flowed down into the fluid reservoir 15 is discharged from the second fluid discharge path 16. The cooling oil discharged from the second fluid discharge path 16 is sent to the heat exchanger 7 by the cooling fluid pump 8. The cooling oil sent to the heat exchanger 7 is cooled in the heat exchanger 7 and then sent back into the electric motor 1.

[0051] <Cooling water flow> 5 and 6, for example, the cooling water supplied from the first fluid supply port 60 flows through the water jacket 62 toward the first fluid discharge port 61 while meandering up and down inside the cylinder 10. This cools the stator core 30 attached to the inner surface of the cylinder 10 and the cooling oil running down the inner surface of the cylinder 10. The cooling water also cools the cooling oil flowing through the heat exchange passage 70 in the heat exchange unit 7.

[0052] <Cross-sectional area of ​​heat exchange passage> Fig. 7 is an explanatory diagram of the flow path cross-sectional area of ​​the heat exchange passage 70 according to the embodiment. Fig. 7 corresponds to a diagram including a cross section of the heat exchange section 7 cut along a plane perpendicular to the axial direction and passing through the discharge port 76. The flow path cross-sectional area corresponds to the cross-sectional area when the flow path is cut along a plane perpendicular to the fluid flow direction (the direction in which the cooling oil flows in this embodiment). 7, the second cooling circuit 5 is configured to include a heat exchange passage 70 formed in the side surface of the housing 2. The heat exchange passage 70 is a passage formed in the heat exchange section 7.

[0053] In the present embodiment, in the heat exchange passage 70, when the flow path cross-sectional area at the first position in the fluid flow direction is defined as the first area A1 and the flow path cross-sectional area at the second position on the downstream side in the fluid flow direction from the first position is defined as the second area A2, A1 > A2 is satisfied. Further, when the flow path cross-sectional area at the third position on the downstream side in the fluid flow direction from the second position is defined as the third area A3, A2 < A3 is satisfied.

[0054] When viewed from one side of the cylindrical body 10, the heat exchange passage 70 overlaps a part of the water jacket 62. When viewed from one side of the cylindrical body 10, the heat exchange passage 70 overlaps one (in the present embodiment, the second straight passage 62A2) of the plurality of straight passages 62A in the water jacket 62.

[0055] In the present embodiment, when viewed from the axial direction along the central axis CL, the heat exchange passage 70 includes a heat exchange horizontal passage 70A (an example of an extending path) that extends in a direction different from that of the second straight passage 62A2 (an example of one of the plurality of straight passages 62A). The heat exchange horizontal passage 70A includes an overlapping portion 70AL that overlaps the second straight passage 62A2 when viewed from one side of the cylindrical body 10. In FIG. 7, the overlapping portion 70AL in the heat exchange horizontal passage 70A connected to the discharge port 76 is shown.

[0056] When viewed from the axial direction, the cylindrical body 10 has a curved surface 10A that curves toward the overlapping portion 70AL. When viewed from the axial direction, the lid portion 72 has a flat surface 72A facing the overlapping portion 70AL. The overlapping portion 70AL is defined by the curved surface 10A of the cylindrical body 10 and the flat surface 72A of the lid portion 72 in the thickness direction of the lid portion 72.

[0057] When viewed from the axial direction, the second straight passage 62A2 is formed to be curved in an arc shape along the circumferential direction of the cylindrical body 10. When viewed from the axial direction, the curved surface 10A of the cylindrical body 10 is formed along the radially outer edge portion of the second straight passage 62A2. When viewed from the axial direction, the portion (wall portion) of the cylindrical body 10 having the curved surface 10A is sandwiched between the second straight passage 62A2 and the overlapping portion 70AL.

[0058] The first position is an upstream position in the fluid flow direction of the overlapping portion 70AL in the heat exchange horizontal passage 70A. The second position is a central position in the fluid flow direction of the overlapping portion 70AL. The third position is a downstream position in the fluid flow direction of the heat exchange horizontal passage 70A in the fluid flow direction of the overlapping portion 70AL. The flow path cross-sectional area of ​​the heat exchange horizontal passage 70A gradually decreases from the first position to the second position. The flow path cross-sectional area of ​​the heat exchange horizontal passage 70A gradually increases from the second position to the third position. The flow path cross-sectional area of ​​the heat exchange horizontal passage 70A is smallest at the second position (second area A2) between the first position and the third position.

[0059] In the heat exchange horizontal passage 70A, the flow passage cross-sectional area at a position upstream in the fluid flow direction from the first position is larger than a first area A1. In the heat exchange horizontal passage 70A, the flow passage cross-sectional area at a position downstream in the fluid flow direction from the third position is larger than a third area A3.

[0060] As an example, the formula for calculating the heat transfer coefficient is shown below. In the following formula (1), h is the heat transfer coefficient [W / (m 2 ·K)], k is the thermal conductivity of the object [W / (m·K)], δ T indicates the thermal boundary layer [m], respectively.

[0061]

number

[0062] As shown in the above equation (1), the heat transfer coefficient h is the temperature boundary layer δ T The smaller the value of , the higher the temperature boundary layer δ T The value of becomes smaller. In other words, as the fluid velocity V increases, the heat transfer coefficient h increases. Note that the above formula (1) is only one example of a formula for calculating the heat transfer coefficient.

[0063] In this embodiment, in the heat exchange passage 70, the overlapping portion 70AL has a smaller flow path cross-sectional area than other portions (specifically, portions that do not overlap with the second straight passage 62A2 when viewed from one side of the cylindrical body 10). In other words, in the overlapping portion (overlapping portion 70AL) of the heat exchange passage 70 that overlaps with the portion through which the cooling water passes when viewed from one side of the cylindrical body 10, the flow path width is narrower than other portions. As a result, in the portion that overlaps with the portion through which the cooling water passes, the fluid velocity V increases. That is, in the portion that overlaps with the portion through which the cooling water passes, the thermal conductivity increases and the cooling performance improves.

[0064] In the example of the figure, the overlapping portion 70AL in the heat exchange horizontal passage 70A connected to the discharge port 76 is described, but the overlapping portions 70AL in other heat exchange horizontal passages 70A may have the same configuration. For example, in the overlapping portions 70AL of each of the plurality of heat exchange horizontal passages 70A arranged in the vertical direction, it may be configured to satisfy A1 > A2 and A2 < A3 for the flow path cross-sectional areas. For example, the magnitude relationship of the flow path cross-sectional areas in each overlapping portion 70AL is not limited to the above and can be changed according to the design specifications.

[0065] <Operational Effects> As described above, the electric motor 1 of this embodiment includes a housing 4 that houses the rotor 2 and the stator 3, and a heat exchange unit 7 that is integrated with the housing 4 and cools the cooling fluid. The heat exchange unit 7 is configured to include a heat exchange passage 70 formed on the side surface of the housing 4. When the flow path cross-sectional area at the first position in the fluid flow direction of the heat exchange passage 70 is the first area A1 and the flow path cross-sectional area at the second position downstream of the first position in the fluid flow direction is the second area A2, A1 > A2 is satisfied. According to this configuration, by satisfying A1 > A2, the flow path cross-sectional area at the second position in the heat exchange passage 70 becomes smaller than that at the first position, so the flow velocity increases. When the flow velocity increases, the heat transfer rate increases and the thermal resistance decreases. That is, at the second position, heat is more easily transferred than at the first position, so the heat of the cooling oil is more easily transferred to the cooling water. Therefore, the cooling performance can be improved.

[0066] In the present embodiment, when the cross-sectional area of the flow path at the third position downstream of the second position in the fluid flow direction is defined as the third area A3, A2 < A3 is satisfied. According to this configuration, in the heat exchange passage 70, the cross-sectional area of the flow path at the second position is smaller than that at the third position, so the flow velocity increases. When the flow velocity increases, the heat transfer coefficient increases and the thermal resistance decreases. That is, heat is more likely to be transferred at the second position than at each of the first position and the third position, so the heat of the cooling oil is more likely to be transferred to the cooling water. Therefore, the cooling performance can be further improved.

[0067] In the present embodiment, in the first cooling circuit 6 (cooling water circuit 6), a passage through which cooling water flows as the first fluid is formed. In the second cooling circuit 5 (cooling oil circuit 5), a passage through which cooling oil flows as the second fluid is formed. The heat exchange part 7 is an oil cooler for cooling the cooling oil. According to this configuration, cooled cooling oil can be supplied to the cooling oil circuit 5, so the cooling performance can be further improved. In addition, since an external oil cooler is not required, the number of parts can be reduced.

[0068] In the present embodiment, the housing 2 includes a cylindrical cylinder body 10. In the cooling water circuit 6, a water jacket 62 that meanders in one direction and the other direction parallel to the central axis CL of the cylinder body 10 through the inside of the cylinder body 10 and is continuous in the circumferential direction of the cylinder body 10 is formed. When viewed from one side of the cylinder body 10, the heat exchange passage 70 overlaps a part of the water jacket 62. According to this configuration, in the overlapping portion of the heat exchange passage 70 and the water jacket 62, the cooling oil flowing through the heat exchange passage 70 can be cooled by the cooling water flowing through the water jacket 62. Therefore, since cooler cooling oil flows through the cooling oil circuit 5, the cooling performance can be further improved.

[0069] In this embodiment, the water jacket 62 is formed in a straight line parallel to the central axis CL, and is composed of a plurality of straight passages 62A arranged at intervals in the circumferential direction, a first end passage 62B formed to connect two first ends of the straight passages 62A adjacent to each other in the circumferential direction, and an other end passage 62C formed to connect two other ends of the straight passages 62A adjacent to each other in the circumferential direction and arranged alternately with the first end passage 62B in the circumferential direction. When viewed from one side of the cylinder 10, the heat exchange passage 70 overlaps one of the straight passages 62A. According to this configuration, the cooling oil flowing through the heat exchange passage 70 can be cooled by the cooling water flowing through one of the straight passages 62A at a portion where the heat exchange passage 70 overlaps with one of the straight passages 62A as viewed from one side of the cylinder 10. In addition, it is easier to make the heat exchange section 7 smaller than when the heat exchange passage 70 overlaps with each of the straight passages 62A as viewed from one side of the cylinder 10.

[0070] In this embodiment, when viewed from the axial direction along the central axis CL, the heat exchange passage 70 includes an extension path 70A (heat exchange horizontal passage 70A) that extends in a direction different from one of the plurality of straight passages 62A. When viewed from one side of the cylindrical body 10, the heat exchange horizontal passage 70A includes an overlapping portion 70AL that overlaps with one of the plurality of straight passages 62A. The second position is a central position in the fluid flow direction of the overlapping portion 70AL. According to this configuration, the flow passage cross-sectional area is smaller at the center position (second position) in the fluid flow direction in the overlapping portion 70AL than at other positions, so that the fluid velocity V is faster. T Therefore, the cooling performance in the overlapping portion 70AL can be improved.

[0071] In this embodiment, the heat exchange section 7 comprises a wall portion 71 that opens the heat exchange passage 70 to one side of the cylindrical body 10, and a lid portion 72 that is connected to the wall portion 71 and closes the heat exchange passage 70 from one side of the cylindrical body 10. According to this configuration, the wall 71 of the heat exchanger 7 can be integrally molded with the cylindrical body 10, and thus the heat exchanger 7 can be easily manufactured. In addition, by providing the lid 72 that is connected to the wall 70 and closes the heat exchange passage 70 from one side of the cylindrical body 10, it is possible to prevent the cooling oil from leaking to the outside.

[0072] In this embodiment, the cylindrical body 10 has a curved surface 10A that curves toward the overlapping portion 70AL when viewed from the axial direction. The lid portion 72 has a flat surface 72A that faces the overlapping portion 70AL when viewed from the axial direction. According to this configuration, an overlapping portion 70AL can be formed by the curved surface 10A of the cylindrical body 10 and the flat surface 72A of the lid portion 72. This eliminates the need for complex machining of the lid portion 72, thereby enabling cost reduction.

[0073] In this embodiment, the first position is a position upstream of the overlapping portion 70AL in the fluid flow direction in the heat exchange horizontal passage 70A. The flow path cross-sectional area of ​​the heat exchange horizontal passage 70A gradually decreases from the first position toward the second position. According to this configuration, the flow passage cross-sectional area of ​​the heat exchange horizontal passage 70A gradually decreases from the first position to the second position, so that the flow velocity gradually increases from the first position to the second position, and the flow velocity is maximum at the second position. Therefore, the cooling performance can be smoothly improved at the overlapping portion 70AL. In addition, the hydraulic loss can be suppressed.

[0074] In this embodiment, the third position is a position downstream of the overlapping portion 70AL in the fluid flow direction in the heat exchange horizontal passage 70A. The flow path cross-sectional area of ​​the heat exchange horizontal passage 70A gradually increases from the second position toward the third position. According to this configuration, the flow passage cross-sectional area of ​​the heat exchange horizontal passage 70A gradually increases from the second position to the third position, so that the flow velocity gradually decreases from the second position to the third position and reaches a maximum at the second position. Therefore, the cooling performance can be smoothly improved at the overlapping portion 70AL. In addition, the hydraulic loss can be suppressed.

[0075] <Modification> In the above-described embodiment, when the flow path cross-sectional area at the third position on the downstream side in the fluid flow direction from the second position is defined as the third area A3, an example where A2 < A3 was described, but the present invention is not limited thereto. For example, A2 ≥ A3 may be satisfied. For example, the magnitude relationship between the second area A2 and the third area A3 can be changed according to the design specifications.

[0076] In the above-described embodiment, a passage through which cooling oil flows as the first fluid is formed in the first cooling circuit, a passage through which cooling water flows as the second fluid is formed in the second cooling circuit, and the heat exchange section was described by taking an example of an oil cooler for cooling the cooling oil, but the present invention is not limited thereto. For example, the heat exchange section may be a radiator for cooling the cooling water. For example, the heat exchange section may be configured to have both a function of cooling the cooling oil and a function of cooling the cooling water. The configuration mode of the heat exchange section can be changed according to the design specifications.

[0077] In the above-described embodiment, the housing includes a cylindrical body, and the heat exchange section was described by taking an example of being integrally formed with a part of the outer periphery of the cylindrical body, but the present invention is not limited thereto. For example, the heat exchange section may be integrally formed over the entire outer periphery of the cylindrical body. Further, the heat exchange section may be integrated with the cylindrical body by bolt fastening. The arrangement mode of the heat exchange section with respect to the cylindrical body can be changed according to the design specifications.

[0078] In the above-described embodiment, in the first cooling circuit, a first fluid passage that meanders in one direction and the other direction parallel to the central axis of the cylindrical body through the inside of the cylindrical body and is continuous in the circumferential direction of the cylindrical body is formed. When viewed from one side of the cylindrical body, the oil cooler was described by taking an example of overlapping with a part of the first fluid passage, but the present invention is not limited thereto. For example, when viewed from one direction of the cylindrical body, the heat exchange section may not overlap with the first fluid passage. The arrangement mode of the heat exchange section with respect to the first fluid passage can be changed according to the design specifications.

[0079] In the above-mentioned embodiment, the first fluid passage is formed in a straight line parallel to the central axis, and is arranged at intervals in the circumferential direction, and includes a one-end side passage formed to connect two one-end sides of the straight passages adjacent to each other in the circumferential direction, and an other-end side passage formed to connect two other-end sides of the straight passages adjacent to each other in the circumferential direction, and arranged alternately with the one-end side passage in the circumferential direction. The heat exchanger is overlapped with one of the straight passages as viewed from one side of the cylinder, but is not limited to this. For example, the heat exchanger may overlap each of the straight passages as viewed from one side of the cylinder. The arrangement of the heat exchanger with respect to the straight passages can be changed according to the design specifications.

[0080] In the above-described embodiment, the plurality of straight passages includes a first straight passage, a second straight passage, and a third straight passage that are arranged in sequence at intervals in the circumferential direction, and the heat exchanger is arranged between the first straight passage and the third straight passage and overlaps with the second straight passage when viewed from one side of the cylinder, but this is not limiting. For example, the heat exchanger may overlap with each of the first straight passage, the second straight passage, and the third straight passage when viewed from one side of the cylinder. The arrangement of the heat exchanger with respect to the first straight passage, the second straight passage, and the third straight passage can be changed according to design specifications.

[0081] In the above embodiment, the heat exchange unit is disposed between the one end passage and the other end passage when viewed from one side of the cylinder, but this is not limiting. For example, the heat exchange unit may be disposed across the one end passage and the other end passage when viewed from one side of the cylinder. The arrangement of the heat exchange unit relative to the one end passage and the other end passage can be changed according to design specifications.

[0082] In the above embodiment, an example has been described in which, as viewed from one side of the cylinder, the heat exchange section has continuous heat exchange passages in a direction parallel to the central axis while meandering in one direction and another direction intersecting one of the multiple straight passages, but this is not limited to the example. For example, the heat exchange section may have continuous heat exchange passages in a direction parallel to the central axis while meandering in one direction and another direction parallel to one of the multiple straight passages. The form of the heat exchange passages can be changed according to the design specifications.

[0083] In the above embodiment, the heat exchange passage includes an extension passage that extends in a direction different from one of the straight passages when viewed from the axial direction along the central axis, the extension passage includes an overlapping portion that overlaps with one of the straight passages when viewed from one side of the cylindrical body, and the second position is a central position in the fluid flow direction at the overlapping portion, but this is not limited to the above. For example, the second position may be an upstream position or downstream position in the fluid flow direction at the overlapping portion. For example, the aspect of the second position can be changed depending on the design specifications.

[0084] In the above embodiment, the oil cooler includes a wall portion that opens the heat exchange passage to one side of the cylinder, and a lid portion that is connected to the wall portion and closes the heat exchange passage from one side of the cylinder, and an example has been described in which the cylinder has a curved surface that curves toward the overlapping portion when viewed from the axial direction, and the lid portion has a flat surface facing the overlapping portion when viewed from the axial direction, but this is not limited to this. For example, the cylinder may have a flat surface facing the overlapping portion when viewed from the axial direction. For example, the lid portion may have a curved surface that curves toward the overlapping portion. For example, the configuration of the cylinder and the lid portion facing the overlapping portion can be changed according to design specifications.

[0085] In the above embodiment, the first position is an upstream position in the fluid flow direction from the overlapping portion in the extension path, and the flow path cross-sectional area of ​​the extension path is gradually reduced from the first position to the second position. However, the present invention is not limited to this. For example, the flow path cross-sectional area of ​​the extension path may be reduced stepwise or abruptly from the first position to the second position. For example, the mode of the flow path cross-sectional area of ​​the extension path can be changed according to the design specifications.

[0086] In the above embodiment, the third position is a downstream position of the overlapping portion in the extension path in the fluid flow direction, and the flow path cross-sectional area of ​​the extension path gradually increases from the second position to the third position. However, this is not limited to the above. For example, the flow path cross-sectional area of ​​the extension path may increase stepwise or steeply from the second position to the third position. For example, the mode of the flow path cross-sectional area of ​​the extension path can be changed according to the design specifications.

[0087] In the above-described embodiment, the heat exchange unit includes a wall portion that opens the heat exchange passage to one side of the cylinder body, and a cover portion that is connected to the wall portion and closes the heat exchange passage from one side of the cylinder body. However, the present invention is not limited to this. For example, the heat exchange unit may be built into the cylinder body. For example, the manner in which the heat exchange unit is integrated into the housing can be changed according to the design specifications.

[0088] In the above-described embodiment, an example has been described in which an inlet for introducing cooling oil into the heat exchange passage is formed at one end side in a direction parallel to the central axis of the wall portion, and an outlet for discharging cooling oil from the heat exchange passage is formed at the other end side in a direction parallel to the central axis of the wall portion, but this is not limited thereto. For example, the inlet and outlet for cooling oil may not be formed in the wall portion. For example, the inlet and outlet for cooling oil may be formed in the lid portion. The form of the inlet and outlet for cooling oil may be changed according to the design specifications.

[0089] In the above-described embodiment, the electric motor is mounted on an electric swing shovel, and an electric swing motor for swinging an upper swing body of the electric swing shovel has been described as an example, but the present invention is not limited thereto. For example, the electric motor may be mounted on other work machines such as a wheel loader, a bulldozer, or a dump truck. For example, the electric motor may be configured as a drive motor for driving a work machine or a drive motor for driving a traveling device. The aspect of the work machine on which the electric motor is mounted and the target driven by the electric motor can be changed according to the design specifications.

[0090] In the above-described embodiment, the electric motor is vertically disposed so that the rotor shaft is parallel to the rotation axis, but the present invention is not limited to this. For example, the electric motor may be horizontally disposed so that the rotor shaft is perpendicular to the rotation axis. For example, the electric motor may be disposed at an angle so that the rotor shaft crosses the rotation axis at an angle. The arrangement of the electric motor may be changed according to the design specifications.

[0091] In the above embodiment, the electric motor is an inner rotor type electric motor in which a stator is disposed outside a cylindrical rotor, but the present invention is not limited to this. For example, the electric motor may be an outer rotor type electric motor in which a stator is disposed inside a cup-shaped rotor. The type of the electric motor may be changed according to the design specifications.

[0092] Although one embodiment has been described above with reference to the drawings, the specific configuration is not limited to the above, and addition, omission, substitution, and other modifications of the configuration are possible without departing from the spirit of this disclosure, and the above-mentioned embodiments can also be combined as appropriate. [Explanation of symbols]

[0093] Reference Signs List 1...electric motor, 2...rotor, 3...stator, 4...housing, 5...cooling oil circuit (second cooling circuit), 6...cooling water circuit (first cooling circuit), 7...heat exchange section, 10...cylinder, 10A...curved surface, 40...space, 62...water jacket (first fluid passage), 62A...vertical straight passage (straight passage), 62A1...first straight passage, 62A2...second straight passage, 62A3...third straight passage, 62B...upper horizontal passage (one end side passage), 62C...lower horizontal passage (other end side passage), 70...heat exchange passage, 70A...heat exchange horizontal passage (extension path), 70AL...overlapping section, 71...wall section, 72...lid section, 72A...flat surface, CL...central axis

Claims

1. a housing that accommodates the rotor and the stator; a heat exchanger integrated in the housing for cooling a cooling fluid; The heat exchange unit includes a heat exchange passage formed in a side surface of the housing, When a flow path cross-sectional area of ​​the heat exchange passage at a first position in the fluid flow direction is defined as a first area A1 and a flow path cross-sectional area of ​​the heat exchange passage at a second position downstream of the first position in the fluid flow direction is defined as a second area A2, A1>A2 is satisfied. Electric motor.

2. When a flow path cross-sectional area at a third position downstream in the fluid flow direction from the second position is defined as a third area A3, A2<A3 is satisfied.

2. The electric motor of claim 1.

3. a first cooling circuit formed integrally with the housing and through which a first fluid flows; The heat exchange unit cools at least one of a second fluid different from the first fluid.

3. The electric motor according to claim 2.

4. a second cooling circuit through which the second fluid flows; The first cooling circuit is formed with a passage through which cooling water flows as the first fluid, The second cooling circuit is formed with a passage through which cooling oil flows as the second fluid, The heat exchange unit is an oil cooler for cooling the cooling oil.

4. The electric motor according to claim 3.

5. The housing comprises a cylindrical body, The first cooling circuit has a first fluid passageway that passes through the inside of the cylinder, meanders in one direction and the other direction parallel to the central axis of the cylinder, and is continuous in a circumferential direction of the cylinder, When viewed from one side of the cylindrical body, the heat exchange portion overlaps with a portion of the first fluid passage.

5. An electric motor according to claim 4.

6. The first fluid passage is A plurality of linear passages formed in a straight line parallel to the central axis and spaced apart from one another in the circumferential direction; a first end passage formed to connect two first ends of the plurality of linear passages adjacent to each other in the circumferential direction; the linear passages are formed so as to connect two other ends of the linear passages adjacent to each other in the circumferential direction, and the linear passages are configured by the one-end side passages and other-end side passages arranged alternately in the circumferential direction, When viewed from one side of the cylindrical body, the heat exchange passage overlaps with one of the plurality of straight passages.

6. An electric motor according to claim 5.

7. When viewed in an axial direction along the central axis, the heat exchange passage includes an extension path that extends in a direction different from one of the plurality of linear passages, the extension path includes an overlapping portion that overlaps one of the plurality of linear paths when viewed from one side of the cylindrical body, The second position is a center position of the overlapping portion in the fluid flow direction.

7. An electric motor according to claim 6.

8. The oil cooler is a wall portion that opens the heat exchange passage to one side of the cylindrical body; a cover portion connected to the wall portion and closing the heat exchange passage from one side of the cylindrical body, 8. An electric motor according to claim 7.

9. When viewed from the axial direction, the cylindrical body has a curved surface that curves toward the overlapping portion, When viewed in the axial direction, the cover portion has a flat surface facing the overlapping portion.

9. An electric motor according to claim 8.

10. the first position is an upstream position of the overlapping portion in the fluid flow direction in the extension path, A flow path cross-sectional area of ​​the extension path gradually decreases from the first position to the second position.

10. An electric motor according to claim 9.

11. the third position is a downstream position of the extension path in the fluid flow direction relative to the overlapping portion, A flow path cross-sectional area of ​​the extension path gradually increases from the second position toward the third position.

11. An electric motor according to claim 9 or 10.

12. A running body, An upper rotating body supported on the traveling body so as to be rotatable about a rotating shaft; A work machine operably supported on the upper rotating body; The electric motor according to any one of claims 1 to 10, which is configured as a rotation motor for rotating the upper rotating body relative to the traveling body; A work machine comprising:

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